What are all the holes in the dash for on my 1964 C10

[1964_C10]

Hi I'm new to this forum. I have just bought a 1964 Chevy C10 Fleet side Short bed with a 350 with some aftermarket cam and a wiring nightmare! And I'am wondering what the three holes on the left side of the steering column are suppose to have installed in them. My truck has one out of three on the left side with something in them (which is the headlight knob). If someone knows what the other holes are suppose to have in them i would be so grateful!